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Old 01-27-2012, 08:08 AM
TRBenj TRBenj is offline
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Originally Posted by topwrench
Ok well the 72c is a good trans. I see your point,you would defenetly have to shorten the shaft
Ive seen them behind 6V53 Detroits n they hold up.
Ok on sticking with what youve got,have you checked to see if you can change the BWs input rotation by just moving the thrust washers from front to rear or vice-versa,I know on big trans thats what we do.
Just for curiosity.Do u run the the spring torsional coupling on the 72C or a centa or vulkan?
Another consideration I neglected to mention is clearance to the hull... anything bigger than the 72C wouldnt fit- its within 1/2" of the bottom of the boat. We also have minimal clearance between the output flange of the trans and the shaft log... just barely enough to fit the dripless packing system in there.

You can switch the direction of rotation on the velvet drives by indexing the pump. But you cant spin them full power in reverse. EI, the rotation of the engine (in fwd) has to match the direction of rotation of the prop. To turn a RH prop (required for proper performance with this hull), you need to turn a RH engine (with a BW), or find a trans that switches the direction of rotation (like a ZF Hurth or a PCM 1.23:1), allowing you to use a LH (standard rotation) motor.

Im not familar with your terminology (spring torsional coupling, centa, vulkan), but the transmission mates to the engine with a spring loaded damper plate, which we replaced with new last year. We do not use any dampers between the output coupling of the transmission and the driveshaft- these are not required on boats this size. When used in this application, its oftentimes a bandaid to cure the symptoms of a bad engine/trans damper or misaligned powertrain.
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